Hybridization and Female Albinism in Colias Philodice and C. Eurytheme. a New Hampshire Survey in 1943 with Subsequent Data

Abstract

The gradually advancing incursion of the orange-colored alfalfa butterfly (Colias eurytheme) into the north-eastern States, still abundantly populated by its near relative, the sulphur-yellow clover butterfly (C. philodice), is attended with measurable natural hybridization. This is more conveniently studied in a region such as this where eurytheme, formerly absent, is still relatively uncommon. In other eastern localities where eurytheme may exceed philodice in abundance, detection of hybrids, owing to the extreme variability of eurytheme, is more difficult.